GFS2: Ensure workqueue is scheduled after noexp request

This patch closes a small timing window whereby a request to hold the
transaction glock can get stuck. The problem is that after the DLM has
granted the lock, it can get into a state whereby it doesn't transition
the glock to a held state, due to not having requeued the glock state
machine to finish the transition.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 52f747858f55..aec7f73832f0 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1047,9 +1047,13 @@ int gfs2_glock_nq(struct gfs2_holder *gh)
 
         spin_lock(&gl->gl_spin);
         add_to_queue(gh);
-        if ((LM_FLAG_NOEXP & gh->gh_flags) &&
-            test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
+        if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
+                     test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
+                gl->gl_lockref.count++;
+                if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+                        gl->gl_lockref.count--;
+        }
         run_queue(gl, 1);
         spin_unlock(&gl->gl_spin);